This invention relates generally to tools and instruments of a type and size to be hand-manipulable and, more particularly, to a modular system of hand tools consisting of one or more tool pieces which require reconditioning from time to time and a toolpiece holder or handle to which the tool piece is detachably secured.
Even though machine shops usually employ skilled personnel to sharpen tools and instruments, it is becoming more and more commonplace to use modular tool systems to reduce costs and better insure the availability of properly sharpened tools. Basically, under the modular concept a machine shop, for example, maintains a supply of tool pieces with properly sharpened edges which can be be releasably fixed on a tool holder so as to be easily removed when it becomes dull or damaged and replaced by a sharp one. Thus, a machining operation is interrupted for only the time required to remove a chipped or dull tool and replace it with another taken from a supply kept in optimum condition by an expert hired for the purpose.
A somewhat analogous situation exists in the field of orthopaedic surgery in that skilled services are available for sharpening surgical tools, but the case is rare that the sharpening service is on the hospital premises. Instead, the people providing such services offer to call at the hospital on a regular schedule, say, every month or two, to pick up the tools needing sharpening, but unless the volume of work is significant experience has shown they will not show up. Moreover, although such sharpening services can sharpen and return tools with a relatively short turnaround time, because the surgeon never knows whether he is going to need a particular tool an hour later, two hours later or maybe not until next week, there is a tendency on the part of hospital staff to send instruments out for sharpening only if they are badly damaged. While many hospitals designate in-house personnel to sharpen surgical instruments instead of using outside sharpening services, more often than not such personnel lack sufficient training to be truly expert in the techniques necessary to insure the finest tooling. This long-recognized problem is exacerbated by the recent adoption and growing use of the technique of coating hardened stainless steel surgical cutting instruments to increase the Rockwell hardness and strength of the cutting tip. All of the cutting instruments used in orthopaedics are made of stainless steel because it does not oxidize when sterilized, the cutting edges of which are usually made of 440C stainless which has a hardness between about 55 and 60 on the Rockwell C scale, which is as much as 15 points lower than that of non-stainless tool steels, but which cannot be used in orthopaedic surgery because they would oxidize with sterilization. As a consequence, various coatings, such as titanium nitrate, have been developed which when applied over the hardened 440C stainless steel significantly increases the Rockwell hardness and strength of the cutting tip.
Although such coatings increase the cutting strength of the tip, the sharpened edges do nonetheless become dulled and sometimes chipped with extensive use. Any attempt to sharpen such tips with an abrasive wheel or stone immediately destroys the coating, which is only three-tenthousandth of an inch thick, thereby, in effect, destroying the tool piece. In order that the benefits of coating the cutting edge of stainless steel tool pieces, despite of problem of restoring the edge when it becomes dulled has led to the development of modular techniques in the manufacture of cutting implements utilized in orthopaedics. These techniques, which may be equally applicable and useful in the fabrication of wood carving and stone carving tools, for example, consist essentially of making a relatively small tool piece of hardened stainless steel and coating its sharpened edge to increase the strength and hardness, and then detachably securing the tool piece to a suitable handle by which the tool piece can be manipulated. In this way, when a surgeon first notices that the cutting edge of a tool piece he is using or plans to use is damaged, he can simply remove and dispose of the damaged tool piece, get a replacement tip from a supply cabinet, sterilize it, and attach it to the handle without delaying the surgical procedure.
The construction of currently available modular orthopaedic tools of which applicant is aware, makes tool piece replacement inconvenient and time-consuming, due to the fact that the tool piece is secured to a handle with set-screws and/or bolts which require some form of tool for loosening and re-tightening. Moreover, such attaching means interrupt the contour of the working end of the tool which desirably is smooth and without protuberances or depressions of any kind.
Accordingly, it is a primary object of the present invention to provide an improved modular hand tool system.
Another, more specific, object of the invention is to provide a modular hand tool system especially useful in orthopaedics which includes a multiplicity of cutting tools such as chisels, gouges, osteotomes, and the like, each adapted to be releasably secured to a handle with a finger-operated screw mechanism contained in the handle.